The iPod Touch is a portable media
player, personal digital assistant, and Wi-Fi mobile platform
designed and marketed by Apple Inc. The product was launched
in September, 2007. The iPod Touch has a multi-touch screen
and a graphical user interface. Originally it was available
with 8, 16, or 32 GB of flash memory; the current line includes
models with 8, 32, and 64 GB.
iPod with supplied earbuds
I purchased the iPod Touch model
MB528LL, Version 2.2.1, about six months ago for $240.00 (www.apple.com/ipodtouch
). It has a capacity of 8 GB and a tiny internal piezo-electric
speaker. The iPod's sound is essentially unintelligible at a
distance of more than 12 inches from the device. The original
iPod did not include a speaker.
I have no interest in using the
iPod's audio output to listen to music although it boasts an
easily accessible plug for headphone listening. I use it almost
exclusively as a remote control. As such, it selects the album
to play no audio signal from the iPod enters my listening
chain. However, because millions of people use iPods as a source
of music and video entertainment, I am curious about its frequency
response, distortion, output impedance, channel separation,
maximum output, square wave reproduction, and S/N ratio.
To list all the features of the
Apple iPod Touch would require too much space. Most of the features
will never be used by me and possibly most buyers. The Touch
does not have cell phone capability. It does have e-mail ability.
These features permit me to leave my laptop at home for short,
out-of-town trips accompanied only by the iPod Touch.
The iPod remotely controls my hard-drive,
computer-based CD/DVD player/recorder. To date, I have loaded
about 30 albums onto my computer's HD in the Apple lossless
format. The Touch can operate the iTunes application on my computer
from almost anywhere in my house by means of Wi-Fi. The "Remote"
application, a free download from the iTunes store, controls
album selection, volume control, rapid advance within a selected
CD-based music is imported into
the iTunes library by inserting an audio CD into your computer's
disc drive and clicking on "Import CD." If you have
an Internet connection, iTunes will (usually) automatically
retrieve the song's title, artist, and other information. The
tracks can also be loaded onto the iPod Touch if you want.
The iPod's color screen displays
a list of the tracks available on the computer's iTunes library;
if the music has also been loaded onto the iPod Touch, a display
of the album cover art is also offered. The track listing, name
of artist, and much more are available with a few easily memorized
steps. The iPod permits music selection also by searching for
a song title, artist, etc. It is a nice addition to my computer-based
playback system. I am using iTunes now in place of Microsoft's
Media Center, because the latter was problematic and didn't
include a few features I wanted. The MS Remote Control, for
example, cannot fast-forward within a CD track, and it employs
infrared to communicate with the MS audio software. Infrared
roughly requires line-of-sight for consistent connectivity.
The Media Center only displays album artwork on the computer's
monitor and not on the companion remote. The information on
the computer's monitor, however, was consistently more useable
and the print size larger than what is displayed on the monitor
To control the iTunes software audio
level, there is a volume up/down button and the touch icons
are brightly displayed on the smallish screen. The touch icons
provide the primary access to iPod's many applications and iTunes.
The photo below illustrates the
CD/DVD album display capability of the portable media player
with Apple's CoverFlow (available only for media that has been
loaded onto the iPod). One selects an album by touching the
desired album cover. The selected CD is exhibited and the play
options for the album are displayed.
It takes time to learn where and
how to touch only one button at a time. Even after months of
use, it still often takes me several tries to select the desired
feature or application. One gets the sense that the iPod was
designed for people with extremely small fingers. The built-in
RF feature is great but it has problems. It sends signals inconsistently
to the computer. It often requires multiple button pushes and
random' aiming to obtain some sort of consistent control.
Often when the CD/DVD player does not respond, I reorient the
iPod so that the RF signal path is established. (Remember, the
iPod isn't communicating directly with the computer, but rather
with the Wi-Fi base station, which takes some getting used to!)
Connectivity, Size, and Battery
I have found the iPod's Wi-Fi unpredictable
and inferior for connecting to the web when compared to the
built-in Wi-Fi connectivity of my Toshiba Qosmio Laptop Computer.
On several occasions, I have placed the iPod and the Toshiba
side by side. The laptop easily links to the ISP or web site
while the Touch remains unconnected to the hub. A trip back
to the Apple store declared my Touch was working fine; however,
the unpredictable ISP connectivity continues. Often when out
of town, it sometimes fails to connect to the hotel's router
even though others using laptop computers are surfing the web
and having fun.
The iPod Touch weighs in at 4.05
ounces. The size in inches: 4.3 high x 2.4 wide x 0.33 deep.
The high quality 3.5 inch (diagonal) widescreen, multi-touch
display has a 480-by-320 pixel resolution at 163 pixels per
iPod showing dimensions
There is an interesting UK review
The unit has a built-in rechargeable
lithium ion battery. Apple claims up to 36 hours of music playback
time when fully charged. I could get no more than two hours
of continuous use. The battery is not user replaceable, and
Apple charges $79 to swap your iPod for a new (or refurbished)
one. If your model is not in stock, a comparable iPod will be
The audio output level of the iTunes
software is controlled by a volume up/down button on its side
and an icon on the glass display. All touch icons are brightly
displayed on the smallish screen. These images provide the primary
access to the iPod's many applications and iTunes.
The iPod Touch has a 3.5-mm stereo
headphone jack and a unique Apple "Dock Connector."
A cable plugged into the Dock Connector terminates in a USB
plug for the computer. The computer's USB port provides power
for the iPod, updates, and the ability to Sync' with the
iPod (to transfer photos, songs, videos, etc., from the computer
to the iPod Touch).
Memory and Costs
The iPod Touch memory size is available
now in 8, 32 and 64GB. The most expensive unit with the largest
memory sells for $399.00 from Apple. For my use the smallest
memory size works. It holds about 23 of the thirty albums on
my computer. It will not display all the albums if the playlist
CDs exceed the internal memory capacity. To get around the memory
limitation, I use a custom Playlist containing only the songs
I want to hear. With Remote, I can also access all the material
on the computer's iTunes library, albeit without the fancy CoverFlow
display on the iPod Touch. Furthermore, I could not justify
the huge price difference for additional memory which costs
Apple incrementally so little. Although the original iPod Touch
models were the same except for memory capacity, the two larger
models in the latest generation have faster processors and a
few additional features.
Apple claims a 2020,000 Hz
response for the iPod Touch. No distortion or level-dependent
information is shown in the literature supplied with the iPod.
To perform the following tests, I imported the CBS Records CD-1
into iTunes in Apple Lossless format. After connecting the iPod,
the Syncing process placed the CD onto the iPod. The iPod's
headphone jack was then connected to my computer-based audio
analysis software, SpectraPlus (a PHS product that retails for
$295$1295, depending on selected options). SpectraPlus
provided a complete spectral analysis of the iPod's audio signal.
To my surprise, the iPod Touch did
very well in the tests. All tests were run on a fully-charged
battery, and the iPod's volume control was set to maximum. The
audio signal from the iPod fed my desktop computer's E-mu 1616M
PCI outboard converter. A 30 kHz low-pass filter was used in
Maximum Output and Distortion: The
maximum output and distortion with no load at 1 kHz was 1.04
dBV rms and 0.009% THD. The numbers did not change for loads
between 300 to 600 ohms. The unit is easily able to cope with
most headphone impedances because the output impedance approaches
the ideal, 0.9 ohms. The S/N ratio was 79.5 dB. At a more
likely 0.5 dBV rms output level, the distortion was 0.014% and
the S/N was 76 dB. The 2nd through 5th harmonic distortion
components never exceeded 75 dB. The IMD was 0.008% using
the IM standard 60 and 7,000 Hz tones.
Frequency Response at 0.75 dVB rms
output, both channels into 300 ohms: 1716,000 Hz was flat.
Between 1820 kHz the unit was down 0.1 dB, excellent.
The highest THD occurred at 12.5 kHz, 55.5 dB, good. Channel
separation was typically 50 dB, OK. The output imbalance
between channels never exceeded 0.7 dB at 18 kHz, good.
Square Wave Performance: A small
ripple was visible, typical for A/D converters. The ringing
occurred at the leading edge of the 1 kHz square wave, very
With iTunes and the iPod Touch,
you can import and manage your CD music collection. Place an
audio CD into your computer's disc drive and click Import CD/DVD.
In my system the iPod's audio output is unused.
The Apple iTunes Touch presents
a nearly distortion-free signal to almost any headphone. The
frequency response is smooth and good enough to drive a decent
quality hi-fi system, if desired. I only tested audio quality
with Apple lossless compression, so I can't say how lossy compression
(AIFF or MP3) would affect these results.
The tiny buttons on the iPod Touch
take time to get used to. To date, I'm finding it almost impossible
to select a button without touching an adjacent key. The short-lived
internal battery is only good for about two hours of manipulating
iTunes, because keeping Wi-Fi active uses a lot of power. The
iPod must be connected to the computer's USB port, or an external
AC adaptor, for recharging. The unit will operate with the connection
cable plugged in.
The home screen has a list of icons
for the available applications that are too numerous to list
and for me go mainly unused. Lest anyone forget, it plays music
too. The touch includes Apple's Cover Flow, a handy way of browsing
albums by cover. Currently, the iPod Touch is serving as my
iTunes remote control for my media center until something more
reliable and with larger print comes along.
Alvin Foster October